Disclaimer: If you recognize it, it almost certainly does not belong to me. Although, I'd take Sheldon, or Peter Vincent anytime

Please note that this takes place at the beginning of Season 3 and is AU. Very, very AU. The guys are just returning home from the Arctic, after doing Sheldon's monopole experiments. That much you may recognize. Anything after that, I make no promises.

Also note that there will be Adult Themes, including blood. If such things disturb you… better give this a miss.

Spoilers for "Fright Night"

Thanks to SpaceAnJL for enabling, letting me bounce ideas off of her and for help in a thousand other ways. All mistakes are entirely my own.

Part 1

Leonard Hofstadter, Howard Wolowitz and Raj Koothrappali trudged into the apartment building at 4311 Los Robles after a long cold time at the Arctic. They were complaining about the extreme conditions, how dreadful it had been and how glad they were to be home.

The final member of their little band of scientists was confused by them "I don't know what expedition y'all were on, but I thought that it was a hoot and a half." Sheldon Cooper's Texas twang, usually buried, came out just a little.

The guys gave him a disbelieving look, and started on their way to the stairs when a curvy blonde popped her head out of apartment 1A. "Oh, I thought you were the delivery guys." She was about 5 foot 9, with straight, long blond hair, dark brown eyes, and wearing a body hugging dress. Only Sheldon seemed unmoved by her attractiveness.

"Hi," said Leonard awkwardly.

"Hi." She said back.

"Hi," Leonard repeated.

"Oh, no, not again." Sheldon said with a moan.

"I'm Vivienne," the woman said after staring in bemusement at the guys.

The others scrambled to introduce themselves as Sheldon finished his trek up the stairs. He deposited the load that he was carrying in his apartment, noting that Penny must have aired it as he had requested.

Knowing that assumptions were to be avoided where Penny was concerned, and also knowing that Leonard would be distracted by Vivienne for a few moments, Sheldon decided to inform Penny of their return, and seek reassurance that she had followed his instructions.

Knock, knock, knock, "Penny," he began his ritual knock on their neighbor's door.

Knock, knock, knock, "Penny,"

Knock, knock, knock, "Penny," he finished, wondering if she were home, as she didn't always let him finish it.

The door burst open, and Penny flew at him. "I never thought I'd miss that OCD knock of yours Sheldon. Welcome home," she blurted as she embraced his stiff form.

He cautiously allowed his arms to fold awkwardly around her for a few seconds. "Yes, well, thank you. I must say that I am not displeased to see you again, Penny."

She pulled back with a headshake. "Yeah, thanks, Sheldon." Her eyes scanned his face. "Nice beard. You look good with it." She collected her memory. "Very Spock-like," she offered.

He gave her pleased smile. "Thank you, Penny."

She looked behind him. "Where's Leonard?"

"He is currently meeting our new neighbor, Vivienne."

"Oh," Penny said with a worried frown marring her usually sunny face.

"Did you do as I asked, Penny?" At her blank look. "In regards to our apartment?"

"Oh, yeah, Sheldon." She reassured him absently. She hesitated and then asked, "Did you notice anything…weird about Vivienne?"

Sheldon stared at her in puzzlement and then apparently made some kind of connection in his big Sheldon-y brain. "She is not more attractive than you are, and will not be replacing you as the 'Queen Bee' of our social group."

Penny's racing mind stuttered to a halt. "What? No, that's not…what?" She blinked up at him. "Th-thanks, Sweetie, but I'm actually more worried about… here, come in, will ya'?" She grabbed his wrist and gently pulled him into her apartment, unaware of the other guys gaping at them in shock from the top of the stairs.

"I knew I should have gone straight over to Penny's," Leonard said with a whine in his voice.

"Yeah, 'cause it's first come first serve," was Howard's sarcastic rejoinder.

"Man, I just can't catch a break," Leonard said.

Inside Penny's apartment, she offered Sheldon some tea, and once it was made settled beside him on the sofa. "There is something really weird about that Vivienne, Sheldon." She confided to him.

Sheldon stared at her in consternation. "Are you jealous of her?" He asked bluntly.

She sighed. "I thought so at first, to be honest. But, she really acts weird."

"In what way does she act 'weird'?" Sheldon asked after a pause. Penny was far more adept at social mores than Sheldon was, and he was willing to accept that she had noticed something peculiar about the new neighbor.

"It's really hard to put into words, Sheldon. She's old-fashioned, but that's not really that weird. So are you kinda'. But her responses to things I say is…off. I don't how else to explain it. It's almost like she's reading from a script, playing a part."

Sheldon held her eyes. "What precisely do you expect me to do about it?"

"Nothing, really. I just know that you're much smarter than I am, plus you have your Vulcan superpowers. I thought maybe if you were actually paying attention, you might notice what I noticed. Or see whatever it is I'm missing to make her make sense." She shrugged, hoping the combination of truth and flattery would push the balance to her side.

"I see." He stared thoughtfully into the space above Penny's left shoulder for a few moments. "If you are genuinely concerned, and not merely jealous," he said with a stern look at her, "then I will attempt to ascertain if there is anything peculiar about her."

Penny heaved a relieved sigh. "Thank you, Honey. It means a lot to me. I really hope I'm just jealous. Because the alternative is that our new neighbor is a freakin' vampire. And I just don't see how that can be possible."

"Vampire!" Sheldon's voice rose. He stood abruptly. "You think she's a vampire?"

"Silly, right? But Sheldon, I'm completely serious."

He grabbed her hand and pulled her across the hall to his apartment. He ignored the guys lounging on the sofa as he dragged Penny into his room.

"Sheldon?" She asked hesitantly, as he released her and began searching through a binder.

"One moment, please, Penny." He said. He finally found what he'd been looking for, and showed her picture in his binder. "Do you recognize this emblem?"

Penny blinked for a minute, clearly chasing a memory, "Yeah, she has this tattooed on her shoulder. Sheldon, what the hell is it?"

"I believe that you are correct in your assessment. She is a vampire. That emblem is for one of the classic vampire tribes."

Penny's shoulders drooped. She had been hoping that logical Sheldon would tell her that there was no possible way that Vivienne could be a vampire. She had assumed that Sheldon, king of Apocalypse preparation would know about vampires. "So what do we do, Sheldon?"

"We need to collect more data."

"I'm really worried about the guys."

Sheldon looked at her strangely. "The guys?"

"They'll be all over her. What if she eats them?"

Oh," he said. Then "Oh," again when actual comprehension hit him. "We will, of course, warn them."

"They'll never believe she's a vampire, Sheldon. And then we'll lose credibility." She was proud of herself for trotting out that concept.

Sheldon favored her with a searching look. "Indeed. Then we will have to seek confirmation and assistance prior to informing them."

"Assistance?"

"Yes, there is a man who specializes in vampire lore and, if rumor is to be believed, has successfully hunted them. I will contact him after we confirm."

"And just how do you plan to confirm it, Sweetie?"

"We shall have to search her apartment."

"Wow, that's kinda' illegal, Sheldon. Are you sure you want to do that?"

"It's for the greater good. Sacrifices must be made."

Penny was impressed with Sheldon; not only did he believe her, but he was willing to break the law to help her prove it. The smile she gave him was warm, which confused him. They were in the midst of a potentially very serious situation, why was she smiling at him? And with apparent affection. Still, he found himself smiling back at her.

When they walked back into the living room a few minutes later Leonard, Howard and Raj stared at them in surprise. "Hi, guys," Penny said warmly. "Welcome home." Leonard shook himself out of his shock and moved to hug her. She returned it without hesitation. She also hugged Raj, and suffered through an overly-friendly hug from Howard. She sat down and asked about the expedition. Sheldon, who, due to distraction, had remained surprisingly quiet about their findings, immediately started bragging about proving String Theory. It was when he was bragging about the Nobel he was certain to win that Penny caught the expressions on the other guys' faces. Guilty awkwardness mixed with smugness.

"Guys?" She finally prodded.

Penny didn't understand what exactly a can opener had to do with Sheldon's experiment, but she understood the betrayed expression on Sheldon's face.

"Why would you do that?" Sheldon asked in a stunned voice.

"You were being a pain in the ass." Howard replied bluntly.

"So you sabotaged my work?" Sheldon was a genius, but could not comprehend why his ersatz friends would do such a thing.

"Come on Sheldon, no harm done." Leonard sounded like he was talking to a child.

"No harm?" Sheldon's voice went very high and Texas-y.

"Seriously, guys, you screwed up his work?"

"Penny, Penny, Penny, you don't understand science stuff, so just sit there and look pretty." Howard said.

"Well, I may not understand 'science stuff', but you boys clearly don't understand a damn thing about professionalism or friendship. How could you do that?"

"You weren't there, Penny. You have no idea what he was like." Leonard said/whined.

"He was different than he is every day?"

"Well, no, but we were all stuck in that little hut."

She gaped at him for a few long seconds. She was clearly as shocked as Sheldon was and more than a little disappointed. She turned her attention to Sheldon. "Sweetie, I'm going back to my place, do you want to come over for a little while?" She asked gently.

A shell-shocked Sheldon blinked at her for a few seconds, then rose and followed her. He sat in his spot at her apartment. "I can't believe they would do such a thing." Sheldon finally said.

"No, Sweetie, me neither." She raised her hand to pat him in consolation, but stopped herself.

"I thought they …," his voice trailed off.

"I know, Sheldon. I expected better of Leonard, if not the other two."

"He's my best friend." His little-boy-lost sad eyes were making her eyes fill with empathetic tears.

"I know," she said quietly.

They sat quietly for a long time. Penny was hesitant to remind him of their self-appointed task; Vivienne could wait. It was Sheldon himself who brought his focus back to their vampy neighbor.

"We'll wait until after sundown, and scout out Vivienne's apartment, Penny." He said commandingly. It felt good to him to have some control over something, even if was vampire hunting with Penny.

After sundown they watched Vivienne leave the building, and then the two of them cautiously made their way down to the first floor, armed with a couple of tiny video cameras to install in Vivienne's apartment. They knocked on her door, and when no one answered, Sheldon picked the lock (earning a shocked look from Penny), and they eased their way into the apartment.

While Sheldon hid the mini cameras, Penny looked around the apartment. There was no overt evidence that Vivienne was a vampire, but there were no mirrors either, which Penny found suspicious. There was also a banner, with the same emblem that Sheldon had shown her hanging on the wall. Penny took a photo of it with her cell phone.

When they were getting ready to leave the apartment, there was a sound in the hall. Penny leaned against the door, with her ear pressed to the wood, while Sheldon stood behind her, peering out the peep hole. Once they were convinced that the way was clear, they exited and returned to Penny's apartment where they set up the monitoring equipment.

They split their attention between the monitors and the TV, where they watched the "Lord of the Rings" trilogy.

Nothing happened for a long time; they made it through the first movie. Part of the way through the second movie Vivienne's door opened and a man walked in, apparently kissing nothing. Penny and Sheldon looked at the screen, then each other.

"Oh, God," said Penny. "I really wanted to be wrong."

They watched as the man's shirt unbuttoned itself, and his pants followed. Penny and Sheldon shared an uncomfortable look. "You're recording this as evidence, right?" Penny asked.

"Of course."

"Then I don't think we need to watch, do you?"

"No, no I don't." He was happy to agree. He shut off the video, and returned his attention to the television.

The movie ended but neither made a move to get up. Sheldon didn't want to admit that he was a little frightened now that vampirism had been confirmed. Penny was certainly able to protect herself and perhaps him if he stayed close to her. That was not even taking into consideration that he really didn't want to share quarters with Leonard right now. The trick was getting her to ….

"Do you want to sleep here tonight, Sheldon? I know it's not…."

"Yes," he interrupted. He didn't know why she had suggested it, but he certainly didn't want her to change her mind.

She blinked at him in surprise. "Oookay, um, you can sleep on the couch and…."

"Penny, Penny, Penny. You know that won't work. I sleep in a bed. And remember my big Cornish head."

"I had forgotten about that." She hesitated. She really did not want to be alone in her apartment now. She sighed, If it had been any other male of her acquaintance they'd be sharing the bed, but oh, no not Sheldon. She sighed again. "All right, Honey, but no more poetry. Do you want to go get your pajamas, while I make up the sofa?"

"Thank you, Penny." He said meekly.

Sheldon returned to his apartment, where Leonard, Howard and Raj were watching television. He ignored them, an attitude that they returned. Although, when he returned in his pajamas and headed to the door, he had their undivided attention.

"Where ya' going, Sheldon?" Leonard asked.

"Not that the matter is any of your concern, but I'm sleeping at Penny's tonight."

"O-on the sofa?" Leonard squeaked.

"That's insane on the face of it. I'll be sleeping in Penny's bed, of course."

"Again?"

"Again?" Chorused Howard and Raj.

"Yeah, Sheldon got locked out, while we were in Vegas, and stayed at Penny's." Leonard's tone was bordering on hostile.

"Yes, and now if you'll excuse me, Penny is waiting." He spared them a last disdainful look and left.

The guys followed him to the door, and watched Penny let him in after his ritual knock. She was wearing "Hello Kitty" shorts and a tank top. She looked over and saw the guys. She pursed her lips in anger, and closed the door.

"I just can not catch a break," Leonard whined.